[R] question about matrix one column values matching a vector of values

[Henrique Dallazuanna]

Use %in% indeed of '=='

a[a[,1] %in% b,]


On 09/03/2008, Waverley <waverley.paloalto at gmail.com> wrote:
> Hi,
>
> I have a matrix
> a = matrix (1:16, 4, 4)
> b = c (2,3)
>
> I want to find out which rows of a, where a[,1] equals any values of b?
>
> I know that if b is only one value, e.g, b=2, then what I want is a[a[,1] ==
> 2,]
>
> But what about if it is not one value but a vector of values?
>
> Thanks much in advance.
>
> --
> Waverley @ Palo Alto
>
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-- 
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O